Grinding mill



@91,750 Si. BJERRE GRINDIN'G. 'MILL jan. 1, i929. l

Filed may 19, w25 2 snq'e'gs-sneet l w 4-- y l W,

6 l 0 150 2g. o 95 INI/Ewan 'Zam Bjerfe` By hub 5, rig. 2,

ythe upper grinding member hub 5 and the Patented Jan. l, 1929.

SILIAM BJERRE, F SKIVE, DENMARK.

GRINDIN G MILL.

Application filed May 19, 1925, Serial No. 31,335, and in Denmark .Tune 6, 1924.

The present invention relates to the type of grinding mill which comprises a statlonary and a rotaryv grinding member, one of whlch is moved in axial direction relatively to the other one if the mill is overloaded, and the invention has for its object to provide a mill the two grinding members of which may easily be separated from `one another without their adjustment being thereby altered, and the supplyof grain'to which is adjusted automatieally in such a4 mannelthat if a certain permissible loading is exceeded, then one of the grinding members is moved automatically in axial direction away from the other grinding member, whereby the mill becomes unloaded inore or less. AThis movement of the said grinding member may be utilized simultaneously, according to the present invention, to actuate the grain supply device for instance the oscillating, trayvof the same, in such a manner that the supply of grain is reduced until the excess load disappears.

rl`he present invention involves a simple form yof mill which is easy to take apartand easy to adjust, and various constructions of the same 'are illustrated on the drawing,

Fig. 1 shows a Vertical section of one embodiment of the mill with' axially movable non-rotary grinding member,

Fig. 2 shows the same in top view, Fig. 3 shows thesame in side elevation, Fig. 4 is a longitudinal section of a mill the rotary grinding member of which is axially movable, Fig. 5 is a longitudinal section of a modified embodiment of the mill shown in Figs. l to' 3. The principal distinguishing feature of the present mill is that it is fitted with a stationary shaftl, Fig. 1, about which the rotary grinding member 2 is journalled as well as the non-rotary grinding member 3. In the embodiment shown the shaft 1 is vertical, and 3 has rigidly connected to it a hub 5 provided with upper and lower guide collars 6 and 7 through which the shaft passes; the upper collar resting-on a supporting collar 4 fixed on the shaft. The grinding member 3 are loose on the shaft 1, but are prevented from'following the rotation of the grinding member 2 by means of an arm 8 projecting from the and held in contact with a stationary-portionof the mill, forinstance the cover 9 of the dust case 23, by a helical kspring 46.

come the torsional moment 5 and resting on the collar The rotary grinding member. 2 is attached to a hollow shaft 10. The latter encircles the shaft l and is guided about the same by means of ball-bearings 12, the lower one of which `rests on a shoulder or collar 1l on the' shaft 1. The shaft 10 is rotated about the shaft 1 by means of a belt-driven pulley 13 on the shaft 10. i

The two grinding members 2 and 3 are pressed against one another partly by the dead weight lof the grinding member 3 and partly by a spring 14 encircling the shaft l and interposed between the lower collar 7 and a nut 15 screwed onto the shaft 1. The said nut is held securely in position by means of a lock-nut 16 on which the collar 4 is supported. By'means of a screw 17 the collar 4 is guided in a longitudinal groove 18 in the shaft 1, in such a mann er that it cannot rotate relatively to the shaft. By rotation of the nut 16 the collar 4 is moved axially. whereby the space between the two adjacent grinding surfaces of the grinding members'2 and 3 may be adjusted.

The grain or the like to be ground is supplied to the mill by way of a hopper 19 and an oscillating tray or other discharge element '21 of known construction disposed below the said hopper. The said oscillating tray is disposed on top of the mill and conveys the grain to anaperture 50 in the cover 9 whence the grain slides down into a central recess 40 in the grinding tray is operated by a cam or cams .20 provided on a sleeve 41 which encircles the shaft 1, and is connected to the shaft 10, Fig. 1, in such a manner that it follows the rotation of the latter so that during the rotation of the shaft 10. the cam 20` strikes the side of the tray. A spring 45 (Fig. 2) tends to keep the oscillating tray in contact with the sleeve 41.

memberl 3. The oscillating If for some reason or other the mill is overloaded, for instance by foreign bodies entering into the space between the grinding members 2 and 3, then the friction between the lat` ter will exceed a certain predetermined value `whereby the torsional moment of the-friction acting on the grinding member 3 will over'- of the Vspring 46 acting on the vsame grinding member by Way of the arm 8.' The hub 5 with the grindingv member 3 provided thereon will then rotate about the shaft 1, whereby vran adjustable'v screw 22 attached to the top guidejrof the'hub 4 will, slide on the of the screw 22 is slidably received, the saidI screw will be lifted, thereby raising the hub 5 and the grinding member 3 so that the latter will be lifted above the grinding member 2,'

and the load on the mill will thus be relieved. When thel cause of the excessive loading is removed, tbe spring 46 will return the grinding member 3 into the position shown in Fig. 1.

he grinding members are encased in a dust casing 23 which is closed by the cover 9. The bottom. portion of the hub 5 is annular. and is filled in a central opening in thecover 9, whereby a lateral guide for the hub 5 and, thereby, for the sha ft 1 is secured.

The oscillating tray 21 is suitablyjournailed in such a manner that rotation of hub 5 (or a lug or arm on the same) during excessive loading will swing the oscillating tray more or less outward,'i. e. away from the cam or cams 20. The latter will then actuate the oscillating tray less intensively orvif the hub l5 is rotated considerably-maybe not at all, whereby the supply of grain will become reduced or entirely stopped, respectively, until the excess load disappears.

It will be apparent from the above that the two grinding surfaces may be spaced from one another, when desired, by turning the arm 8 by hand. This is especially of iniportance when the mill is to be started.

The individual 'parts of the present mill may be glven any other suitable shapes than the particular ones shown on VJthe drawing,

without departing from the scope of the invention. Thus the spring 46, for instance, may be omitted, if one end of the spring 14 is connected for instance to the hub 5, and the other end for instance to thenut 15 and if,

when being inserted between these members,

lthe said spring is twisted so muchV that. it

will exert va torsional moment on the grinding-member sufficient to counteract the tendency of the grinding member to follow the rotation of the grinding member 2.

In the construction shown in'Figs. 1 to 3, the grinding member 3 is axially movable on the stationary shaft 1. Infthe construction shown in Figs. 4 and 5 the hub 5 of the grinding member 3 is keyed to the shaft/1', in such Aa manner that a relative axial displacement of `the two grinding members must be efgrinding-member or by the`rotary grinding vmember being moved axially relatively to the stationary shaft.

In the construction s ownin Fig.Y 4, the collar 11 which supports the rotary sh aft V10 is ax,-

ially movable along`v the shaft 1." it being supported by a lever 75, the point of pivotal conneetion of which to said collar is adjustable,

shaft beingl one end of the lever resting on a spring 6G, while thc other end of the said lever is hinged at G9 to an endwise-movable vertical supporting rod G7 adapted to be adjieted by means of a nut G8, in such a manner that the said lever and, hence, the collar 11 may be raised or lowered as desired, whereby the grinding members 2 and 3 will be moved to ward or from one another.

Then the mill is overloaded, the pressure between the grinding members 'will push member 2 while displacing the collar 11 and compressing the spring 6G, the initial tension of which is adjusted in such a manner that il does not allow the said motion of the rotary grinding member to take place until the pressure between the grinding members exceeds a certain predetermined limit.

The nut 68 rests on a bracket Z0 or the like on the mill frame, and the shaft 1 rests in a step-bearing 100.: -I

In the construction shown in Fig. 4, the sta tionary shaft 1 is supposed` to be vertical, but nothing prevents it from being horizontal, while still remaining within the scope of the invention.

In the construction shown in Fig. gtherc is provi ded on the bottom end of the shaft 1 a cam disc (i0 which is enclosed in an oillillcd vessel 47 on the cover 7 3 of which the collar 11 is mounted adjustahly by being screwed down onto a nipple 62 on the cover .downward the'shaft 1() of the rotary grinding 73. Between he cam dise G0 and the cover 73 on the vessel 47 there is inserted a helical spring 6,1 encircling the shaft and having one end connected to the cover 7 3, while the other end thereof is connected to the cam disc- 60.

The helical spring 61 is held in compression in such a manner that it tends to force the shaft 1 downward',4in such a manner that the shaft 1 cannot be raised without overcoming a pressure from the spring 61 adjusted according to the desired pressure between the grinding members. f

The si rift 10 of the rotary grinding member 2 rests, as mentioned above, on the collar 11. Betweenthe latter and the lower end of the shaft 10 there is inserted, however, an adjust-ing nut 82 screwed onto' the nipple 62,4

by means of which nut the shaft 10 and, hence,

the' rotary grinding member may be ad- ]usted suitably in vertical direction, and the collar then screwed firmly aga-inst the bottom face of the nut 82. A

If the mill shown in Fig. 5 is overloaded, .the friction between the grinding members 2 and .3 will result inthe non-rotary grind-A ing member -3 tending to follow the rotation of the rotary grinding member 2. Thereby Vthe shaft 1 onto which-.the grindingl member 3 is keyed will be rotated, and the cam disc 60 will thereby be moved alongthe-top. of V'a tscrew or other stop 63 provided at the botof the vessel 47. The inclined face G4 of 130 1 member 3 may turn through an angle the size 'certaine the nature of my said invention and shaft to whichlone member is secured; a normally stationary shaft extending through fthe the-cam disc 60 engages the said stop 63 ,durin this movement and thereby causes the cam isc 60 and the 'shaft 1 to be raised, whereby the grinding member 3 will be displaced axially away from the grinding member 2 and the overload will be relieved. The tension of the spring 61 is adjusted in such a. mannerthatit will prevent the grinding member 3 from following the rotation of the shaft 1 `as long as the friction between the two grinding members does not exceed a certain limit.

The provision of the cam disc 60 and the spring 61 in the oil-filled vessel 47 contributes i very essentially to reduction of the friction between the cam discv 60 and the stop 63, so

that this friction mayalways be relied on to be of uniform 'value,'and the mill will there- 'fore always be unloaded automatically when one and =the same maximum load has been reached. l

As shown in Fig. 5, the cam on the bottom side of the cam 'disc 60 is furnished with a face 65 at right angles to the-shaft 1.

Consequently 'the shaft 1 with the grinding of which depends on the length of the said face-65 without any elevation of the-shaft 1 and the grinding member 3 being thereby effected. Therefore n'o real unloading of the mill will be effected by relative displacement of the grinding members, but the said angular motion may be utilized to cause, during its duration, a reduction of the motions of the oscillating tray (not shown) inthe same manner as.,exio`1ained in the case of Figs. 1 to' 3.- The reduced, maybe entirely stopped,'motions of the oscillating tray cause the supply of grain to the grinding members v be stopped` partly or entirely, whereby the mill will be unloaded.v Only when foreign bodies penetrate into the space bethe friction bedise 60 so far that theinclined cam face 64 of the same will be moved over the stop 63,

whereby the grinding members willfbecome separated from one another.

If desired, the dust casing 23 may beconnected--iirmly to the grinding member 3 ,in such a manner that it will follow the rotation of thelatter, and the rotation oft e dust casy ing may thenbe utilized to vpush the'. oscillatmg tray away from the cams 20.

Havin now particularly described and asin what manner the same is to be performed, I declare that-what I claim is l 1. A grinding mill, comprisin a pair of coacting grinding members; a ho low, rotary hollow shaft and carrying the other grinding member; a movable element ,to deliver the ond-named grinding member resiliently to the stationary part of the mill, so that when the friction between the grinding members exceed a certain limit, said second-named grinding member will be rotated through an angle against the action of said resilient. connecting means, whereby said movable element will befdisplaced relatively to said oscillating means and the supply of material to the grinding members will be overload disappears.

2. A grinding mill, comprising a pair of reduced until the coaeting grinding members; a rotary shaft to which one member is secured; a normally stationary shaft carrying the other member;

a feed hopper for the material to be: gr nd; a' movable discharge element carried by said members; a sleeve connected to therotary shaft to rotate therewith and provided with a cam; and means for yieldinglyholding said discharge element against said sleeve so as to be oscillated during and cnsequent upon the hopperto deliver the material bctween said l 4. A grinding mill; comprising a hollow ro` tary shaft; driving'iifieans therefor; a grinding member secuied to 'said shaft; a normally stationary shaft extending through the hollow shaft; a yoke carried by the stationary shaft; a grinding member rigidly secured to the yoke for coaction with the first-named member -in grinding material introduced between them; a lfeed hopper; a swinging discharge element'carried by said hopper lfor delivering the material. therefrom to the grinding members; a sleeve secu-red to the rotary shaft to rotate therewith and through which the stationary shaft extends; a' cam on against said sleeve so as to be oscillated .during and consequent upon the rotation ofthe sleeve.

5. A grinding millcomprising a pair of said sleeve to enga e said-discharge element; and means for hol ing the disehargeelement grinding members adapted to .receive material between them to be ground; means for rotating one vof said grinding members; 'means holding the two grinding members in operative relation to each other; and means acting automatically, when the. friction effect between onegrindingmember and the said material exceedsa predetermined limit, to enable that member to move differently f om the normal rotation of the rotary ginging member and to cause the said friction effect. y lto decrease.

material to be ground to the grindingmem- 6. A grinding comprising a pairof lauf'.-

the material tobe --ground to the grinding members; means enabling one of the grinding members-when the friction effect between vthe same and the said material exceeds a predetermined limit, to move different-ly from the normal rotation of the-rotary grinding member and to cause said different motion to'influence the feeding device in a mannerto diminish the supply of material to the grinding members.

7. A grinding mill comprising a pair of grinding members; means for rot-ating one of said members; means holding the two grinding members in operative relation to .each other; a feeding device for delivering the material to be ground to the grinding members; and means acting automatically, when the friction effect between one grinding member and the said material exceeds a predeterminedlimit, to enable that member to move bodily away from the other grinding member and to cause 4such motion to influence the feeding device in a maner to diminish thesupply of material to the grinding members.

8. A grinding mill comprising a rotary grinding member; a normally stationary grindingmember; means holding the two grinding members in operative relation to each other; a` feeding device for delivering thejmaterial to be ground to the grinding members; and means acting automatically, when 'the friction effect between one grinding member and the said material exceeds a predetermined limit, to enable that member to move bodily away from the other grinding member and to influence the feeding device in a n'ianner to diminish the supply of material to the grinding members.

9. A grinding mill comprising a rotary grinding member; a normally stationary grinding member; means for holding the two grinding members inoperative relation to each, other; af feed hopper for the material to be-ground; a movable discharge element carrying the said material to theA e i grinding members.; nmeans connected to be rotated together with the rotary grinding memberfor imparting an oscillating'motion tosaid discharge element;\meansacting automatically, when the fricton eil'ect vbetween one grinding memberand lthe saidv material exceedsa predetermined limit, to enable that member to move bodily away from the othergrinding member; and means to reduce the movements of the discharge element in order to diminish the supply of material to the grinding members when such excess friction occurs.y l

10, A grinding mill, comprising a pair of coactmg grinding members; a rotary shaft to which one member is secured; a normally stationary shaft carrying the other member;

a feed hopper for the material to be ground;

a movable discharge element carried by saidc hopper to deliver the. material between said members; a sleeve connected to the rqtary shaft t-o rotate therewith and provided with a cam; means for yieldingly holding said discharge element against said sleeve so as to be oscillated during and consequent upon the rotation of the sleeve; means for enabling the grinding members to move bodily avay from one another when the friction effect between said material and said grinding meInbers exceeds a predetermined limit; and means acting automatically to reduce y the oscillation of the discharge element when such excess friction occurs.

11. A grinding mill, comprising a hollow rotary shaft; y driving means therefor; a S5 grinding member secured to said shaft; a normally stationary shaft extending through the hollow shaft; a yoke ca-rried by the stationary shaft; a grinding member rigidly secured to the yoke for coaction with the firstnamed member 'in grinding material introduced between-them; a feed hopper; a swinging discharge element carried byA said hopper for delivering the material therefrom to the grinding members; a sleeve sse-,95 cured to the rotary shaft to rotate therewith and through which the stationary shaft extends; a cam sleeve to engage' said discharge element; means for holding the discharge element against said sleeve so as to be'oscillated during and consequent upon the rotation of the sleeve; a supporting memberfixed to the stationary shaft and carrying the Said yoke, said supporting member having an inclined face to cause axial displacement of the yoke and the grinding member `attached thereto, if that grinding member is forced to rotate due to an overload of the mill; and means for reducing the movement of the discharge element when the normally stationary grinding member is rotated.

ll2. A grinding mill, comprising a rotary shaft; a grinding member secured thereto; aV normally stationary shaft; a grinding member loosely carried thereby ;..a feeding device for-the material to be ground; a movable element to deliver the material from the `feeding device to the grindingimembers;

means connected to beA rotated by'the rotary shaftforimparting an oscillating motion to said movable element; and means acting automatically, when thefriction effect between the grinding 'member carried by the stationary shaftand the material exceeds a predetermined limit, to 'enablefthat member to move bodily on said stationary shaft away from the other grinding member.

In testimony whereof he i aiiixes his signature. f

SILIAM BJERRE. 

